In the United States slavery is understandably associated with the South since it was the Southern states that so vigorously defended the practice during the nineteenth century. However, to understand how slavery first took hold in the South, historians look much farther back in time, to ancient Greece and Rome and the civilizations that preceded them. In many of these societies, it was common practice to enslave peoples who had been defeated in war. Even through the Middle Ages, Moors and Christians enslaved each other and justified it on religious grounds. Difficult as it is for us to understand today, slavery was a simple fact of life throughout much of human history.

During the fifteenth and sixteenth centuries, this unquestioning acceptance of slavery combined with two other factors— Europeans’ belief in the inferiority of other races and cultures, and European settlement of the New World&mdash...